An Egyptian military prosecutor ordered the detention of a woman whose rumored captivity in a church triggered deadly clashes between Muslims and Christians, the state news agency said on Thursday.

At least 12 people were killed in fighting that started on Saturday in a Cairo suburb, where witnesses said Salafis -- followers of a strict interpretation of Islam -- had surrounded a church and demanded that those inside release Abeer Fakhry, a woman who allegedly converted to Islam.

Fakhry was sent to a women's prison and was accompanied by her infant daughter, the MENA news agency reported. It did not say why she had been detained and did not list any charges against her.

"The military prosecution ordered the detention of the citizen Abeer Fakhry, the catalyst for the incidents of strife in Imbaba, for 15 days pending investigation," the report said.

Hundreds of mostly Christian protesters gathered by Egypt's main state television building cheered as a priest announced Fakhry had been detained. Several demonstrators said the detention proved the church did not hold anyone against their will.

At least one church was burned during the fighting in the Imbaba suburb after Salafis and Christians exchanged gunfire and threw firebombs and stones at each other, witnesses said. Security forces fired teargas to stop the fighting.The clashes have posed a challenge for Egypt's new military rulers, under pressure to impose security and revive the ailing economy while seeking to avoid the tough security tactics against Islamists used by ex-President Hosni Mubarak.